1. Field of the Invention
This invention relates to furnace grates having transverse rows of grate elements. It is relevant to furnace feed grates for incinerators, for example refuse incinerators.
2. Description of the Prior Art
In a known incinerator feed grate having transverse rows of grate blocks (see Swiss Patent No. 457685), a clamping device comprises two shell members capable of sliding telescopically, to a partial extent, in one another, the members being pressed away from one another in the transverse direction of the grate by a compression spring arranged horizontally between the two shell members, thus forming in the region of a side wall of a combustion chamber an elastically compressible grate boundary wall, the external shell member being incorporated in the refractory brickwork of the combustion chamber side wall and serving as a stationary abutment for taking up the clamping pressure, whereas the internal mobile shell member presses under the action of the compression spring on the outermost block of a transverse row of grate blocks and as a result ensures that the grate blocks situated adjacent one another within the row are pressed elastically against one another so that adjacent grate blocks in the row come to be situated against one another without any gaps between them, at all working temperatures, eliminating the thermal expansion clearance which is provided at the grate assembly stage. This is intended to ensure that, when starting the firing system from cold, and also in the hot state, there will be no fuel losses due to material falling through the grate, during operation slag pieces and foreign substances contained in the fuel cannot get in between the grate blocks, and also that under-grate air will not flow out undesirably between these blocks. A further object is to obviate the undesirable formation of marginal fires in the region of the side walls of the combustion chamber. For the same purpose, in this known feed grate, which is intended for large firing systems, two-part elastically compressible partition walls, each similar in construction to the boundary wall described above, are provided at intervals between individual grate paths, for example two such partition walls between three grate paths. However, in this known grate arrangement the mobile outermost grate blocks and the adjoining portions of the side wall of the combustion chamber are subjected to a considerable rate of wear which is caused by the relatively high clamping pressure of each block clamping device, which is used not only to press the grate blocks within the transverse row elastically against one another but also to press the outermost grate blocks of the transverse row at the same time against the internal shell member of a grate boundary wall. In addition, in this known grate the elastically compressible boundary walls are subjected to the heat of the fire and also to the action of dust and ashes, since they are situated directly below the fire bed. Also it is not possible to lift off and put down the grate together with the clamping device.
There are also known (see East German Patent No. 105048) closure and wearing plates for the ends of transverse grate block rows of mechanical inclined grate firing systems which plates are mounted to be pivotable, in the combustion chamber side walls on an axis of rotation situated outside their mass centre of gravity axis, on a horizontal pin, so that they swing automatically under the effect of their own weight on to the adjacent outermost mobile grate blocks and lean against them. When wear occurs, these lateral wearing and closure plates are intended to swing-in correspondingly so that at all times there will be substantially no gap, and thus in this region combustion air is prevented from passing through from a chamber below the grate upwards into the combustion chamber. But the wear at the plates and the grate blocks is in the first instance relatively considerable since their mutual bearing contact surfaces immediately after the grate is assembled can only be of very limited size and increase in size only during relatively long operation and grinding into one another. Apart from this, the effective sealing pressure on the lateral grate block surfaces continually increases as the pivoting movement of the plates continues, so that the sealing conditions at the plates also continually change in an undesirable manner. But above all, since the outermost grate block is fixed against lateral displacement by a securing means, the problem of gaps between the respective adjacent grate blocks in each of the transverse rows of blocks remains unsolved. A grate which is provided with these known closure and wearing plates also cannot be simply installed or removed along with these plates.